The Siemens 5SU1353-1KK13 is a SENTRON RCBO — a combined residual-current circuit breaker and overcurrent protection device in a single 2-module-wide package. It protects a single-phase final subcircuit against earth leakage and overload/short-circuit, with a 13 A rated current, C tripping characteristic, and 30 mA residual-current sensitivity. Breaking capacity is 4.5 kA per EN 60898.
Ratings and what they mean for fit
The 13 A rating at 30 °C is the headline current for resistive and mixed loads. At 40 °C ambient — common inside a closed distribution board — the continuous rating derates to 12.48 A; at 50 °C it drops to 11.96 A, and at 60 °C to 11.31 A. If your panel ambient runs above 40 °C, size the upstream protective device against the derated figure, not the 30 °C nameplate. C-curve means the magnetic trip fires at 5 to 10 times rated current — 65 to 130 A — suited for circuits with moderate inrush, like small motor loads or lighting banks with electronic ballasts. The 30 mA residual-current element catches ground faults at the threshold required for personal protection in most residential and commercial installations. The 1P+N pole design switches the line conductor and disconnects the neutral, but the neutral pole is not protected against overcurrent — only the line pole has the thermal-magnetic trip. This is standard for single-phase RCBOs in TN or TT systems where the neutral is not switched under load. Overvoltage category III and pollution degree 2 mean the device is rated for fixed installation downstream of the main distribution board, in environments where non-conductive pollution may occur but occasional condensation is expected. IP20 applies only when the distribution board is installed and conductors are connected — the device itself is not sealed against dust ingress.
Mounting and integration
Width is 36 mm (2 modular units) for a standard 35 mm DIN rail. Installation depth is 70 mm; overall depth including terminals is 77 mm. The supply can enter from either the top or bottom — no mandatory orientation. Mounting position is any, so the RCBO can be installed horizontally in a shallow enclosure if needed. Halogen-free and silicon-free construction matters if the panel is in a zone where outgassing from a fault could damage nearby electronics or where silicone contamination must be avoided (e.g., paint shops, semiconductor fabs).